Light Measurement

1. 

The following table shows the results of the experiment described in the video:

The distance between measuring device and light source (cm)Measured amount of light
(lx)
20310
40146
60146
80115
100115
120115
140115
160115
180115
200115

Referring to the above results, check the appropriate box(es):

The distance between measuring device and light source (cm)Positive correlationNegative correlationNo correlation
20 – 80
100 -200

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2. 

The experimental data is shown in the graph below:

(a) Check the appropriate box(es):

Independent VariableDependent VariableControl Variable
Measured amount of light
Distance between the measuring device and the light source
The room temperature of the laboratory

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(b) 

Referring to the above results, which of the following is/are correct?

When the measuring device was at a distance of 2500 mm, the measured amount of light is 200 lx.
When the measuring device was at 3500 mm to 5000 mm, the measured amount of light did not decrease further.
The experimental results can be used to support the inference : “The greater the distance between the measuring device and the light source, the lower the measured amount of light.”

答案錯誤

3. 

The information is shown below :

If the distance between the measuring device and the light source is 600 mm, what is the calculated value of amount of light?

0.5 lx
1 lx
2 lx
3 lx

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Time Measurement

1. 

A student conducted repeated measurements several times in relation to the time. This helps understand __________ of the measurement.

accuracy
precision

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2. 

Which of the following results best describes "high accuracy and low precision"?

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3. 

In the video, students used different instruments to measure the time taken for a tennis ball to fall onto a table. The results are as shown below.

Measured Time (s)
Stopwatch0.160.150.160.16
Synchronous Counter0.1580.1600.1550.158

(a) 

The limit of reading is the smallest interval on the scale of the instrument. What are the limits of reading of the following instruments?

StopwatchSynchronous Counter
0.005 s0.001 s
0.005 s0.0005 s
0.01 s0.001 s
0.01 s0.0005 s

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(b) 

The reading error is the measurements with quantities smaller than half the smallest division on the scale (limit of reading). What are the reading errors of the following instruments?

StopwatchSynchronous Counter
0.005 s0.001 s
0.005 s0.0005 s
0.01 s0.001 s
0.01 s0.0005 s

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4. 

The following graph shows the process of the experiment conducted by students at school.

Which of the following way(s) would obtain more accurate measurement?

Use a red tennis ball instead of a yellow tennis ball.
Use a metal ball instead of a tennis ball.
Use a larger size of tennis ball.
Use a camera with a high frame rate for shooting.
Ensure the cardboard is vertical.
Set up a white background board.

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Sound Measurement

1. 

1. The following are the results of a students’ experiment on measuring sound intensity level:

Distance between the measuring device and the sound source（cm）Measured Sound Intensity level（dB）
548.1
1041.3
1538.3
2037.2
2536.9
3036.7
3536.5

(a) 

Which of the following(s) can be used as a hypothesis for this experiment?

The measured sound intensity level will decrease as the distance between the measuring device and the sound source increases.
The measured sound intensity level will increase as the distance between the measuring device and the sound source decreases.

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(b) 

Referring to the above results, which of the following is / are reasonable inference(s)?

The measuring instrument used in the experiment was not suitable.
When the distance between the measuring device and the sound source is 13 cm, the measured sound intensity level should be between 38.3 to 41.3dB.
When the distance between the measuring device and the sound source is 0 cm, the measured sound intensity level is 48.1 dB.
The measured sound intensity level will decrease as the distance between  the measuring device and the sound source increases.

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(c) 

The students found that when the distance between the measuring device and the sound source was greater than 25 cm, the measured sound intensity level did not show obvious changes. Which of the following is the best explanation for this?

The laboratory is in a completely quiet environment.
There may be background noise in the laboratory that affected the results.
The measurements in the experiment were not precise enough.
The App of the measuring device was not updated.

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2. 

After repeatedly conducting the experiment, students found that the experimental data did not support the established hypothesis. The students should

change the experimental data to support the hypothesis is valid.
repeat the experiment multiple times until the experimental results are in line with the hypothesis.
try to use other experimental methods for back-checking.
ignore the experimental results that do not support the hypothesis.
review the experimental process and instruments to see if there were mistakes.
formulate a new hypothesis that can explain the phenomenon based on the obtained results and conduct experiments.

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3. 

In order to check the validity of the experiment, students conducted the same experiment under different conditions. The experimental results are shown in the graph below.

Referring to the above graph, which of the following is / are correct?

The environment where the experiment was conducted did not affect the conclusions.
The measured sound intensity level is a dependent variable; the distance between the measuring device and the sound source is an independent variable.
The measurement results showed a positive correlation between the distance of the measuring device from the sound source and the sound intensity level.

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